Currently, wearable articles such as disposable diapers, disposable training pants, disposable adult incontinence garments and the like are constructed of various types of sheet- or strip-like materials. These materials may include nonwoven webs formed of synthetic polymer and/or natural fibers (“nonwovens”), polymeric films, elastic strands, strips or sheets, or assemblies or laminates of these materials. In a typical article, nonwovens and/or laminates of various types form at least one component of an outer garment-facing layer (“backsheet”), an inner body-facing layer (“topsheet”) and various internal layers, cuffs, envelopes or other features, depending upon the particular features of the product. The component sheet- or strip-like materials are usually supplied in the form of large continuous rolls, or alternatively, boxes of continuous longitudinal sheet or strip material gathered and folded transversely in accordion fashion.
The articles are typically manufactured on relatively complex manufacturing lines. Supplies of the required materials are placed at the front of each line. As a line requires the materials for the manufacture of articles, it continuously draws the materials longitudinally from their respective supplies. As a particular material is drawn from the supply and proceeds through the line to be incorporated into final product, it may be flipped, shifted, folded, laminated, welded, stamped, embossed, bonded to other components, cut, etc., ultimately being fashioned by the machinery into an incorporated part of the finished product. All of this happens at the economically-required production rate, e.g., 450 or more product items per line per minute. Generally, for purposes of economy, increasing the production rate is an ever-present objective.
A new design for a wearable absorbent article such as a disposable diaper, training pant or adult incontinence undergarment has been developed. The article has features that give it an underwear-brief-like fit, feel and appearance, which consumers may find appealing. Among the features that give it this fit, feel and appearance are elastic bands about respective leg openings that encircle the wearer's legs. The elastic bands may be formed of, for example, one or more strands or strips of an elastic material such as spandex, bonded with one or more strips of nonwoven or film material to form a band-like elastic strip material. On the subject wearable absorbent article design, these elastic bands are affixed or bonded to the outer surface of a substrate outer cover (backsheet) material, with the lower side edges of each of the elastic bands being substantially coterminous with each of the respective leg openings to create a neatly finished, banded appearance. The elastic strip material may be longitudinally strained prior to affixation to the backsheet material, whereby subsequent relaxation of the elastic strip material causes the backsheet material to gather about the leg openings, for improved fit and comfort.
To date, the subject design has been produced only by hand manufacturing or limited machine-assisted manufacturing techniques, at rates that are too low for economically feasible production of the design as a viable (i.e., competitively priced) consumer product.
Among the problems that the design presents is determining how the elastic strip material can be accurately placed and affixed to the substrate backsheet material at locations required by the design and at economically feasible production speeds, e.g., 450 items or more per minute, in a manner that is reliable, minimizes waste, and maximizes consistency and quality of the band placement and affixing process. It is envisioned that strip material will be applied and affixed to substrate backsheet material at laterally varying design-required locations, as the substrate material moves longitudinally through the manufacturing line at production speed. Under these circumstances, one particular problem lies in determining how to rapidly and repeatedly laterally shift back and forth the point at which such strip material enters a joining/bonding mechanism, without causing the typically pliable, cloth-like strip material to “rope” (longitudinally fold or bunch over on itself) before it enters the joining/bonding mechanism.
A potential associated problem lies in regulating the strain of the elastic strip material as it is affixed to a substrate material. If elastic strip material under longitudinal strain is shifted laterally between two points at which it is gripped, this will cause variation in the strain. Thus, shifting elastic strip material laterally as it is being affixed to substrate material may result in variation in the longitudinal strain of the strip material as affixed to the substrate. In some circumstances this may have undesirable effects.
It would be advantageous if a system, apparatus and method existed to address the problems referenced above.